Oral cholestyramine formulation and use thereof

ABSTRACT

The invention relates to an oral formulation for targeted delivery of cholestyramine to the colon, comprising a plurality of cholestyramine pellets that are coated with a diffusion-controlled inner coating and an enteric outer coating. The invention also relates to the use of this formulation in the treatment of bile acid malabsorption.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation under 35 U.S.C. § 111(a) ofInternational Application No. PCT/SE2017/050128, filed Feb. 9, 2017,which claims priority to SE 1650157-7, filed Feb. 9, 2016. Thedisclosure of the foregoing applications are hereby incorporated byreference in their entirety.

The invention relates to an oral formulation for targeted delivery ofcholestyramine to the colon, comprising a plurality of cholestyraminepellets that are coated with a diffusion-controlled inner coating and anenteric outer coating. The invention also relates to the use of thisformulation in the treatment of bile acid malabsorption.

BACKGROUND

Bile acid malabsorption is a condition characterized by an excess ofbile acids in the colon, often leading to chronic diarrhoea. Bile acidsare steroid acids that are synthesized and conjugated in the liver. Fromthe liver, they are excreted through the biliary tree into the smallintestine where they participate in the solubilisation and absorption ofdietary lipids and fat-soluble vitamins. When they reach the ileum, bileacids are reabsorbed into the portal circulation and returned to theliver. A small proportion of the secreted bile acids is not reabsorbedin the ileum and reaches the colon. Here, bacterial action results indeconjugation and dehydroxylation of the bile acids, producing thesecondary bile acids deoxycholate and lithocholate.

In the colon, bile acids (in particular the dehydroxylated bile acidschenodeoxycholate and deoxycholate) stimulate the secretion ofelectrolytes and water. This increases the colonic motility and shortensthe colonic transit time. If present in excess, bile acids producediarrhoea with other gastrointestinal symptoms such as bloating, urgencyand faecal incontinence. There have been several recent advances in theunderstanding of this condition of bile salt or bile acid malabsorption,or BAM (Pattni and Walters, Br. Med. Bull. 2009, vol 92, p. 79-93; Islamand Di Baise, Pract. Gastroenterol. 2012, vol. 36(10), p. 32-44).Dependent on the cause of the failure of the distal ileum to absorb bileacids, bile acid malabsorption may be divided into Type 1, Type 2 andType 3 BAM.

Diarrhoea may also be the result of high concentrations of bile acid inthe large intestine following treatment with drugs that increase theproduction of bile acids and/or influence the reabsorption of bile acidsby the small intestine, such as treatment with ileal bile acidabsorption (IBAT) inhibitors.

The current treatment of bile acid malabsorption aims at binding excessbile acids in the gastrointestinal tract, beginning in the proximal partof the small bowel, thereby reducing the secretory actions of the bileacids. For this purpose, cholestyramine is commonly used as the bileacid sequestrant. Cholestyramine (or colestyramine; CAS Number11041-12-6) is a strongly basic anion-exchange resin that is practicallyinsoluble in water and is not absorbed from the gastrointestinal tract.Instead, it absorbs and combines with the bile acids in the intestine toform an insoluble complex. The complex that is formed upon binding ofthe bile acids to the resin is excreted in the faeces. The resin therebyprevents the normal reabsorption of bile acids through the enterohepaticcirculation, leading to an increased conversion of cholesterol to bileacids to replace those removed from reabsorption. This conversion lowersplasma cholesterol concentrations, mainly by lowering of the low-densitylipoprotein (LDL)-cholesterol.

Cholestyramine is also used as hypolipidaemic agents in the treatment ofhypercholesterolemia, type II hyperlipoproteinaemia and in type 2diabetes mellitus. It is furthermore used for the relief of diarrhoeaassociated with ileal resection, Crohn's disease, vagotomy, diabeticvagal neuropathy and radiation, as well as for the treatment of pruritusin patients with cholestasis.

In the current treatment of hyperlipidaemias and diarrhoea, the oralcholestyramine dose is 12 to 24 g daily, administered as a single doseor in up to 4 divided doses. In the treatment of pruritus, doses of 4 to8 g are usually sufficient. Cholestyramine may be introduced graduallyover 3 to 4 weeks to minimize the gastrointestinal effects. The mostcommon side-effect is constipation, while other gastrointestinalside-effects are bloating, abdominal discomfort and pain, heartburn,flatulence and nausea/vomiting. There is an increased risk forgallstones due to increased cholesterol concentration in bile. Highdoses may cause steatorrhoea by interference with the gastrointestinalabsorption of fats and concomitant decreased absorption of fat-solublevitamins. Chronic administration may result in an increased bleedingtendency due to hypoprothrombinaemia associated with vitamin Kdeficiency or may lead to osteoporosis due to impaired calcium andvitamin D absorption. There are also occasional reports of skin rashesand pruritus of the tongue, skin and perianal region. Due to poor tasteand texture and the various side effects, >50% of patients discontinuetherapy within 12 months.

Another drawback with the current treatment using cholestyramine is thatthis agent reduces the absorption of other drugs administeredconcomitantly, such as oestrogens, thiazide diuretics, digoxin andrelated alkaloids, loperamide, phenylbutazone, barbiturates, thyroidhormones, warfarin and some antibiotics. It is therefore recommendedthat other drugs should be taken at least 1 hour before or 4 to 6 hoursafter the administration of cholestyramine. Dose adjustments ofconcomitantly taken drugs may still be necessary to perform.

In view of these side effects, it would be desirable if cholestyraminecould be formulated as a colon release formulation, i.e. for release ofthe cholestyramine in the proximal part of the colon. Such a formulationmay require a lower dose of cholestyramine and should have betterproperties regarding texture and taste, and may therefore be bettertolerated by the patients. More importantly, colonic release ofcholestyramine should be devoid of producing interactions with otherdrugs and should not induce risks for malabsorption of fat andfat-soluble vitamins, while still binding bile acids in order to reducethe increased colonic secretion and motility. For reasons of patientcompliance, it would furthermore be desirable if the number of pills tobe taken could be kept as low as possible. Each pill should thereforecontain as much cholestyramine as possible.

EP 1273307 discloses preparations for preventing bile acid diarrhoea,comprising a bile acid adsorbent coated with a polymer so as to allowthe release of the bile acid adsorbent around an area from the lowerpart of the small intestine to the cecum. It is shown thatcholestyramine granules coated with HPMCAS-HF or ethyl cellulosedisplayed extensive swelling and bursting under conditions simulatingthe gastric environment.

Jacobsen et al. (Br. Med. J. 1985, vol. 290, p. 1315-1318) describe astudy wherein patients who had undergone ileal resection wereadministered 500 mg cholestyramine tablets coated with cellulose acetatephthalate (12 tablets daily). In five of the 14 patients in this study,the tablets did not disintegrate in the desired place.

Despite progress made in this area, there still is a need for furtherimproved cholestyramine formulations. In particular, there is a need fororal compositions for targeted delivery of cholestyramine to the colon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the sequestration profiles for formulations A, B, and C inan assay simulating the pH of the stomach and the small intestine. FIG.1A shows the results for formulations A, B and C during 6 hours at pH5.5. FIG. 1B shows the results during 2 hours at pH 1 followed by 4hours at pH 6.8. FIG. 1C shows the results for 2 hours at pH 1 followedby 4 hours at pH 7.4.

FIG. 2 shows the relative concentration of cholic acid (%) vs.incubation time (h) for formulations A, B and C in an in vitro SHIME®assay. The results for a comparative experiment using purecholestyramine powder and a control experiment without cholestyramineare also shown.

FIG. 3 shows the relative concentration of chenodeoxycholic acid (%) vs.incubation time (h) for formulations A, B and C in an in vitro SHIME®assay. The results for a comparative experiment using purecholestyramine powder and a control experiment without cholestyramineare also shown.

FIG. 4 shows the relative concentration of deoxycholic acid (%) vs.incubation time (h) for formulations A, B and C in an in vitro SHIME®assay. The results for a comparative experiment using purecholestyramine powder and a control experiment without cholestyramineare also shown.

DETAILED DESCRIPTION OF THE INVENTION

It has been discovered that small and stable pellets of cholestyraminecan be obtained, and that these pellets can be coated with a coatinglayer that prevents release of the pellets until they reach the colon.The combination of small cholestyramine pellets and a colon releasecoating allows the dose of cholestyramine to be reduced to for example1.5 g twice daily. It is believed that this dose of cholestyramine issufficient for binding an excess of bile acids in the colon. Thecomposition disclosed herein further reduces undesired interactions ofcholestyramine with other components in the gastrointestinal tract, suchas other drugs or nutrients.

In one aspect, the invention relates to an oral formulation for targeteddelivery of cholestyramine to the colon, comprising:

-   -   a) a plurality of pellets comprising cholestyramine;    -   b) a diffusion-controlled inner coating around said pellets; and    -   c) an enteric outer coating,

and wherein more than 70% of the cholestyramine is released in thecolon.

The coating layers substantially prevent release of cholestyramine fromthe pellets until they reach the colon.

Preferably, more than 75% of the cholestyramine is released in thecolon, such as more than 80%, or such as more than 85%. More preferably,more than 90% of the cholestyramine is released in the colon.

In another aspect, the invention relates to an oral formulation fortargeted delivery of cholestyramine to the colon, comprising:

-   -   a) a plurality of pellets comprising cholestyramine;    -   b) a diffusion-controlled inner coating around said pellets; and    -   c) an enteric outer coating,

and wherein less than 30% of the cholestyramine is released in the smallintestine.

Preferably, less than 25% of the cholestyramine is released in the smallintestine, such as less than 20%, or such as less than 15%. Morepreferably, less than 10% of the cholestyramine is released in the smallintestine.

The cholestyramine content of the pellets should be as high as possible.The uncoated pellets therefore preferably contain at least 70% w/wcholestyramine, more preferably at least 75% w/w cholestyramine, morepreferably at least 80% w/w cholestyramine, even more preferably atleast 85% w/w cholestyramine and most preferably at least 90% w/wcholestyramine.

In another aspect, the invention relates to an oral formulation fortargeted delivery of cholestyramine to the colon, comprising:

-   -   a) a plurality of pellets comprising cholestyramine and        -   i. at least 7% w/w of a vinylpyrrolidone-based polymer; or        -   ii. a combination of at least 6% w/w of a            vinylpyrrolidone-based polymer and at least 2% w/w of an            acrylate copolymer; or        -   iii. a combination of at least 5% w/w of a vinyl            pyrrolidone-based polymer and at least 3% w/w of an acrylate            copolymer; or        -   iv. a combination of at least 6% w/w of a            vinylpyrrolidone-based polymer, at least 1% w/w of an            acrylate copolymer and at least 10% w/w microcrystalline            cellulose; or        -   v. a combination of at least 5% w/w of a            vinylpyrrolidone-based polymer, at least 2% w/w of an            acrylate copolymer and at least 20% w/w microcrystalline            cellulose;    -   b) a diffusion-controlled inner coating around said pellets; and    -   c) an enteric outer coating.

In one embodiment, more than 70% of the cholestyramine is released inthe colon, preferably more than 75%, such as more than 80%, or such asmore than 85%. More preferably, more than 90% of the cholestyramine isreleased in the colon.

In another embodiment, less than 30% of the cholestyramine is releasedin the small intestine, preferably less than 25%, such as less than 20%,or such as less than 15%. More preferably, less than 10% of thecholestyramine is released in the small intestine.

The presence of specific amounts of a vinylpyrrolidone-based polymer, orof a combination of a vinylpyrrolidone-based polymer and an acrylatecopolymer, in the composition of the pellets allows for a highcholestyramine content. The resulting pellets are stable enough towithstand the conditions necessary for applying the coating layers ontothe pellets.

The diffusion-controlled inner coating and the enteric outer coatingsubstantially prevent release of cholestyramine from the pellets untilthey reach the large intestine, in particular the proximal colon.Additionally, the coating prevents the pellets from bursting. When waterthat diffuses through the coating is absorbed by the cholestyramine, theincreasing volume of the cholestyramine leads to swelling of thepellets. The diffusion-controlled inner coating of the pellets iselastic and is therefore able to withstand the swelling of the pellets.The coating thereby prevents burst of the pellets and premature releaseof the cholestyramine.

Because of its very low solubility, cholestyramine is not “released”from the formulation in that it dissolves from the formulation anddiffuses into the intestine. Instead, the cholestyramine probably stayswithin the gradually degrading structure of the coated pellet.Therefore, as used herein, the term “release” of the cholestyraminerefers to the availability of the cholestyramine to the intestinalcontent in order to bind components (i.e., bile acids) therein.

Pellets

As used herein, the term “pellets” refers to extruded pellets, i.e.pellets obtained through extrusion and spheronization. The preparationof extruded pellets typically comprises the steps of mixing a powderwith a liquid to obtain a wet mass, extruding the wet mass, spheronizingthe extrudate and drying of the wet pellets.

It is essential that the pellets are stable enough to withstandmechanical stress during handling, such as during drying and coating ofthe pellets. The stability of the pellets may be expressed in terms offriability, which is the ability of a solid substance (such as a tablet,granule, sphere or pellet) to be reduced to smaller pieces, e.g. byabrasion, breakage or deformation. A low degree of friability means thatthe solid substance breaks into smaller pieces only to a low extent. Asused herein, friability is defined as the reduction in the mass of thepellets occurring when the pellets are subjected to mechanical strain,such as tumbling, vibration, fluidization, etc. Methods for measuringfriability are known in the art (e.g., European Pharmacopoeia 8.0, tests2.9.7 or 2.9.41).

Experiments have shown that the inclusion of smaller amounts ofvinylpyrrolidone-based polymer and/or acrylate copolymer than specifiedabove results in lower yield and higher friability of the pellets.Although it is not possible to define acceptable friability limits forpellets in general, friability values of <1.7% w/w friability have beenreported as acceptable to withstand stresses associated with fluid bedcoating, handling and other processes (Vertommen and Kinget, Drug Dev.Ind. Pharm. 1997, vol. 23, p. 39-46). For the cholestyramine pellets ofthe present invention, it has been found that a friability of 2.1% isstill acceptable. The friability is preferably lower than 2.0%, morepreferably lower than 1.5%, and even more preferably lower than 1.0%.

The vinylpyrrolidone-based polymer in the pellets may bepolyvinylpyrrolidone (povidone) or a vinylpyrrolidone-vinyl acetatecopolymer (copovidone). Povidone is a linear, water-soluble polymer madefrom N-vinylpyrrolidone. Copovidone (also known as copolyvidone) is alinear, water-soluble copolymer of 1-vinyl-2-pyrrolidone (povidone) andvinyl acetate in a ratio of 6:4 by mass. In a preferred embodiment, thevinylpyrrolidone-based polymer is copovidone.

The acrylate copolymer in the pellets may be any pharmaceuticallyacceptable copolymer comprising acrylate monomers. Examples of acrylatemonomers include, but are not limited to, acrylate (acrylic acid),methyl acrylate, ethyl acrylate, methacrylic acid (methacrylate), methylmethacrylate, butyl methacrylate, trimethylammonioethyl methacrylate anddimethylaminoethyl methacrylate. Several acrylate copolymers are knownunder the trade name Eudragit®.

Poly(ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethylmethacrylate chloride) is a copolymer of ethyl acrylate, methylmethacrylate and a low content of trimethylammonioethyl methacrylatechloride (a methacrylic acid ester with quaternary ammonium groups). Thecopolymer is also referred to as ammonio methacrylate copolymer. It isinsoluble but the presence of the ammonium salts groups makes thecopolymer permeable. The copolymer is available as a 1:2:0.2 mixture(Type A) or as a 1:2:0.1 mixture (Type B). 30% aqueous dispersions ofType A and Type B are sold under the trade names Eudragit® RL 30 D andEudragit® RS 30 D, respectively.

Poly(methyl acrylate-co-methyl methacrylate-co-methacrylic acid) 7:3:1is a copolymer of methyl acrylate, methyl methacrylate and methacrylicacid. It is insoluble in acidic media but dissolves by salt formationabove pH 7.0. A 30% aqueous dispersion is sold under the trade nameEudragit® FS 30 D.

Poly(methacrylic acid-co-ethyl acrylate) 1:1 is a copolymer of ethylacrylate and methacrylic acid. It is insoluble in acidic media below apH of 5.5 but dissolves above this pH by salt formation. A 30% aqueousdispersion is sold under the trade name Eudragit® L 30 D-55.

Further suitable acrylate copolymers include polyethylacrylate-co-methyl methacrylate) 2:1, which is a water-insolublecopolymer of ethyl acrylate and methyl methacrylate. 30% aqueousdispersions are sold under the trade names Eudragit® NE 30 D andEudragit® NM 30 D.

Preferred acrylate copolymers are ammonio methacrylate copolymer,poly(methyl acrylate-co-methyl methacrylate-co-methacrylic acid) 7:3:1,and poly(methacrylic acid-co-ethyl acrylate) 1:1. More preferably, theacrylate polymer is ammonio methacrylate copolymer, and most preferablythe acrylate polymer is polyethyl acrylate-co-methylmethacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.2.

In one embodiment, the pellets comprise cholestyramine and

-   -   i. at least 7% w/w of a vinylpyrrolidone-based polymer; or    -   ii. a combination of at least 6% w/w of a vinylpyrrolidone-based        polymer and at least 2% w/w of an acrylate copolymer.

In a more preferred embodiment, the pellets comprise cholestyramine and

-   -   i. at least 7% w/w copovidone; or    -   ii. a combination of at least 6% w/w copovidone and at least 2%        w/w ammonio methacrylate copolymer.

The pellets may further comprise an excipient such as microcrystallinecellulose. In one embodiment, the pellets comprise from 0 to 20% w/wmicrocrystalline cellulose, such as from 0 to 10% w/w microcrystallinecellulose. In a more preferred embodiment, the pellets comprise from 0to 5% w/w microcrystalline cellulose.

In another embodiment, the pellets are free from microcrystallinecellulose.

In one embodiment, the pellets comprise from 70 to 92% w/wcholestyramine, from 6 to 12% w/w of a vinylpyrrolidone-based polymer,from 2 to 5% w/w of an acrylate copolymer and from 0 to 20% w/wmicrocrystalline cellulose. More preferably, the pellets comprise from80 to 92% w/w cholestyramine, from 6 to 12% w/w of avinylpyrrolidone-based polymer, from 2 to 5% w/w of an acrylatecopolymer and from 0 to 5% w/w microcrystalline cellulose.

In another embodiment, the pellets comprise from 70 to 92% w/wcholestyramine, from 6 to 12% w/w copovidone, from 2 to 5% w/w ammoniomethacrylate copolymer and from 0 to 20% w/w microcrystalline cellulose.More preferably, the pellets comprise from 80 to 92% w/w cholestyramine,from 6 to 12% w/w copovidone, from 2 to 5% w/w ammonio methacrylatecopolymer and from 0 to 5% w/w microcrystalline cellulose.

In another embodiment, the pellets comprise from 70 to 93% w/wcholestyramine, from 7 to 12% w/w of a vinylpyrrolidone-based polymerand from 0 to 20% w/w microcrystalline cellulose. More preferably, thepellets comprise from 70 to 93% w/w cholestyramine, from 7 to 12% w/wcopovidone and from 0 to 20% w/w microcrystalline cellulose.

In yet another embodiment, the pellets comprise from 80 to 93% w/wcholestyramine, from 7 to 12% w/w of a vinylpyrrolidone-based polymerand from 0 to 10% w/w microcrystalline cellulose. More preferably, thepellets comprise from 80 to 93% w/w cholestyramine, from 7 to 12% w/wcopovidone and from 0 to 10% w/w microcrystalline cellulose.

The uncoated pellets rapidly disintegrate under aqueous conditions.However, they are stable enough to withstand the conditions necessaryfor applying the colon release coating onto the pellets.

Diffusion-Controlled Coating

The diffusion-controlled inner coating provides a modified release ofthe cholestyramine, i.e. the cholestyramine is not made available atonce but over an extended period of time. The coating comprises one ormore polymers that are insoluble at any pH value, but that are permeableto water and small molecules dissolved therein. Examples of suchpolymers include, but are not limited to, polyethyl acrylate-co-methylmethacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.2(Eudragit® RL 30 D), poly(ethyl acrylate-co-methylmethacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.1(Eudragit® RS 30 D), poly(ethyl acrylate-co-methyl methacrylate) 2:1(Eudragit® NE 30 D or Eudragit® NM 30 D) and polyvinyl acetate(Kollicoat® SR 30 D). The diffusion-controlled inner coating preferablycomprises poly(ethyl acrylate-co-methylmethacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.2(Eudragit® RL 30 D), polyethyl acrylate-co-methylmethacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.1(Eudragit® RS 30 D) or a combination thereof, and most preferablypolyethyl acrylate-co-methyl methacrylate-co-trimethylammonioethylmethacrylate chloride) 1:2:0.1.

When water is absorbed by the cholestyramine, the increasing volume ofthe cholestyramine leads to swelling of the pellets. Thediffusion-controlled inner coating should therefore be elastic (i.e.,have high elongation at break). Because of the elasticity of thecoating, the coating is able to withstand this swelling. Burst of thepellets and premature release of the cholestyramine is thereby avoided.The elasticity of the coating may be the result of the elasticity of theorganic polymer(s) itself, or may be induced by the addition of aplasticizer. Examples of suitable plasticizers include triethyl citrate,glyceryl triacetate, tributyl citrate, diethyl phthalate, acetyltributyl citrate, dibutyl phthalate and dibutyl sebacate.

Enteric Coating

The enteric coating comprises a pH-sensitive polymer that is stable andinsoluble at the acidic pH values found in the stomach (pH˜1-3) but thatbreaks down rapidly or becomes soluble at less acidic pH values, such asthe pH values found in the small intestine (pH˜6 to 7). Examples of suchpH-sensitive polymers include, but are not limited to, cellulose acetatephthalate, cellulose acetate succinate, hydroxypropyl methylcelluloseacetate succinate, hydroxypropyl methylcellulose phthalate,poly(methacrylic acid-co-methyl methacrylate) 1:1 (Eudragit® L 100),poly(methacrylic acid-co-methyl methacrylate) 1:2 (Eudragit® S 100),poly(methacrylic acid-co-ethyl acrylate) 1:1 (Eudragit® L 100-55),poly(methyl acrylate-co-methyl methacrylate-co-methacrylic acid) 7:3:1(Eudragit® FS 30 D), polyvinyl acetate phthalate, shellac, sodiumalginate, and zein, as well as mixtures thereof. The enteric coatingpreferably comprises a pH-sensitive polymer selected from the groupconsisting of poly(methacrylic acid-co-methyl methacrylate) 1:1,hydroxypropyl methylcellulose acetate succinate and poly(methacrylicacid-co-methyl methacrylate) 1:2. The enteric coating most preferablycomprises hydroxypropyl methylcellulose acetate succinate.

The diffusion controlled and enteric coatings may comprise one or moreadditives, such as acids and bases, plasticizers, glidants, andsurfactants. Examples of suitable acids include organic acids such ascitric acid, acetic acid, trifluoroacetic acid, propionic acid, succinicacid, glycolic acid, lactic acid, malic acid, tartaric acid, ascorbicacid, pamoic acid, maleic acid, hydroxymaleic acid, phenylacetic acid,glutamic acid, benzoic acid, salicylic acid, mesylic acid, esylic acid,besylic acid, sulfanilic acid, 2-acetoxybenzoic acid, fumaric acid,toluenesulfonic acid, methanesulfonic acid, ethane disulfonic acid andoxalic acid, and inorganic acids such as hydrochloric acid, hydrobromicacid, sulphuric acid, sulfamic acid, phosphoric acid and nitric acid.Examples of suitable bases include inorganic bases such as sodiumbicarbonate, sodium hydroxide and ammonium hydroxide. Examples ofsuitable plasticizers include triethyl citrate, glyceryl triacetate,tributyl citrate, diethyl phthalate, acetyl tributyl citrate, dibutylphthalate and dibutyl sebacate. Examples of suitable glidants includetalc, glyceryl monostearate, oleic acid, medium chain triglycerides andcolloidal silicon dioxide. Examples of suitable surfactants includesodium dodecyl sulfate, polysorbate 80 and sorbitan monooleate.

In order to improve the adherence of the coating layer onto thecholestyramine pellets, or in order to minimize the interaction betweenthe coating layer and the cholestyramine in the pellets, a barriercoating may optionally be present as an additional layer between thepellets and the coating layer. A barrier coating may also be presentwhen two different coating layers should be kept physically separatedfrom each other. A particularly suitable material for the barriercoating is hydroxypropyl methylcellulose (HPMC).

A thin layer of a non-sticking agent may ultimately be applied to thecoated pellets. This outer layer prevents the coated pellets fromsticking together, e.g. during storage. Examples of suitablenon-sticking agents include fumed silica, talc and magnesium stearate.

Together, the coating layers substantially prevent release of thecholestyramine from the pellets until they have reached the largeintestine. Additionally, because of the properties of the polymer in thediffusion-controlled inner coating, the cholestyramine is made availableto the large intestine only slowly and during a period of several hours.Preferably, there should be no exposure of the cholestyramine in thesmall intestine, whereas the exposure should be quick once themultiparticulates have passed the ileocecal valve. In one embodiment,less than 30% of the cholestyramine is released in the small intestine,such as less than 20%, such as less than 10%. In a more preferredembodiment, less than 5% of the cholestyramine is released in the smallintestine. In another embodiment, more than 70% of the cholestyramine isreleased in the colon, such as more than 80%, such as more than 90%. Ina more preferred embodiment, more than 95% of the cholestyramine isreleased in the colon.

The coating layers add further weight and volume to the pellets. Thesmaller the size of the pellets, the larger is the impact of the coatingon the volume of the final formulation. However, for reasons of patientcompliance, it is desirable that the total volume of the formulation iskept as low as possible. The coating layers should therefore be as thinas possible. Preferably, the amount of coating in the final formulation(on dry weight basis) is less than 40% w/w, and more preferably lessthan 35% w/w.

The cholestyramine content of the pellets should be as high as possible.The uncoated pellets therefore preferably contain at least 70% w/wcholestyramine, more preferably at least 75% w/w cholestyramine, morepreferably at least 80% w/w cholestyramine, even more preferably atleast 85% w/w cholestyramine and most preferably at least 90% w/wcholestyramine. The cholestyramine content of the final formulation (ondry weight basis) is preferably at least 50% w/w, and more preferably atleast 55% w/w.

The size of the pellets is initially governed by the diameter of thescreen used in the extrusion step. After the extrusion andspheronization steps, the pellets may be sieved to obtain a pelletfraction with a narrow size distribution. The diameter of the uncoatedcholestyramine pellets is preferably from 500 μm to 3000 μm, morepreferably from 750 μm to 2000 μm and even more preferably from 1000 to1600 μm. In a most preferred embodiment, the diameter of the pellets isfrom 1000 to 1400 μm.

The cholestyramine pellets may be prepared in a process comprising thesteps of:

-   -   i) mixing the dry ingredients;    -   ii) adding water, and optionally the acrylate copolymer, to        obtain a wet mass;    -   iii) extruding the wet mass;    -   iv) spheronizing the extrudate; and    -   v) drying the obtained pellets.

The dried pellets may thereafter be sieved in order to obtain pellets ofuniform size.

The dry ingredients in step i) comprise cholestyramine and thevinylpyrrolidone-based polymer, and may optionally comprisemicrocrystalline cellulose.

Because of its physical nature, cholestyramine powder is able to absorblarge amounts of water, which results in considerable swelling of thematerial. In order to prepare a wet mass from dry cholestyramine, it istherefore necessary to add more water than normally would be used forpreparing a wet mass from dry ingredients. Preferably, water is added tothe mix of dry ingredients in an amount of at least 1.5 times the amountof cholestyramine (w/w), more preferably in an amount of at least 1.75times the amount of cholestyramine (w/w), and even more preferably in anamount of at least 2 times the amount of cholestyramine (w/w).

The coating may be applied onto the cholestyramine pellets by methodsknown in the art, such as by film coating involving perforated pans andfluidized beds.

The oral formulation described herein may be administered to a patientin different forms, depending on factors such as the age and generalphysical condition of the patient. For example, the formulation may beadministered in the form of one or more capsules wherein the coatedpellets are contained. Such capsules conventionally comprise adegradable material, such as gelatin, hydroxypropyl methylcellulose(HPMC), pullulan or starch, which easily disintegrates under the acidicconditions in the stomach. The coated pellets are thereby quicklyreleased into the stomach. Thus, in one aspect, the invention relates toa capsule comprising the oral formulation disclosed herein.

Alternatively, the coated pellets may be administered as a sprinkleformulation, the contents of which can be dispersed in liquid or softfood. Such a formulation does not require the swallowing of largercapsules and is therefore particularly useful for infants and smallchildren as well as for older adults. Thus, in another aspect, theinvention relates to a sprinkle formulation comprising the oralformulation disclosed herein. In such a formulation, the coated pelletsmay be contained within a capsule, sachet or stick pack.

The oral formulation disclosed herein provides several advantages overother formulations. The small coated pellets (multiparticulates)according to the present invention are able to easily pass thegastrointestinal tract. This eliminates the risk that the formulation istemporarily held up in the gastrointestinal tract, such as at thestomach or at the ileocecal valve, as is sometimes encountered withmonolithic formulations (such as tablets or capsules that do notdisintegrate in the stomach).

Furthermore, the cholestyramine is made available to the intestinalcontent only when the diffusion controlled inner coating starts beingdegraded in the lower gastrointestinal tract, in particular the colon.The contents of the stomach and the small intestine are thereforeeffectively protected from the cholestyramine, which is a majorimprovement over formulations that directly release the cholestyraminein the stomach or the small intestine.

The low solubility of cholestyramine in aqueous environment prevents therelease of cholestyramine from the formulation to be measured directly.The availability of the cholestyramine to the intestinal content overtime and at different pH values can instead be determined in vitro, suchas by measuring the sequestering capacity of the formulation undersimulated conditions for the gastrointestinal tract. Such a methodinvolves measuring the decreasing amount of free bile acid (i.e., thecompound to be sequestered) in a liquid medium representative of thegastrointestinal tract, as described in the experimental section. Seealso the Official Monograph for cholestyramine resin (USP 40, page3404).

In another aspect, the invention relates to the formulation disclosedherein for use in the treatment or prevention of bile acidmalabsorption.

The invention also relates to the use of the formulation disclosedherein in the manufacture of a medicament for the treatment orprevention of bile acid malabsorption. The invention further relates toa method for the treatment or prevention of bile acid malabsorptioncomprising administering to a mammal in need of such treatment orprevention a therapeutically effective amount of the formulationdisclosed herein.

Bile acid malabsorption may be divided into three different types,dependent on the cause of the failure of the distal ileum to absorb bileacids. Type 1 BAM is the result of (terminal) ileal disease (such asCrohn's disease) or (terminal) ileal resection or bypass. Type 2 BAM isoften referred to as idiopathic bile acid malabsorption or primary bileacid diarrhoea (BAD) and is believed to be the result of anoverproduction of bile acids or caused by a defective feedbackinhibition of hepatic bile acid synthesis. This feedback regulation ismediated by the ileal hormone fibroblast growth factor 19 (FGF19) inman. Finally, type 3 BAM may be the result of cholecystectomy, vagotomy,small intestinal bacterial overgrowth (SIBO), coeliac disease,pancreatic insufficiency (chronic pancreatitis, cystic fibrosis),pancreatic transplant, radiation enteritis, collagenous colitis,microscopic colitis, lymphocytic colitis, ulcerative colitis orirritable bowel syndrome (i.e., diarrhoea-predominant irritable bowelsyndrome (IBS-D)).

The formulation may also be used in combination with an Ileal Bile AcidAbsorption (IBAT) inhibitor. Treatment with IBAT inhibitors, such as inthe treatment of liver diseases, disorders of fatty acid metabolism orglucose utilization disorders, may result in increased levels of bileacids and/or influence the reabsorption of bile acids by the smallintestine, leading to high concentrations of bile acid in the largeintestine and thus causing diarrhoea. This side effect of the treatmentwith IBAT inhibitors may be treated or prevented by treatment with theformulation as disclosed herein. The formulation and the IBAT inhibitormay be administered simultaneously, sequentially or separately.

Thus, in another aspect, the invention relates to the formulationdisclosed herein, for use in the treatment or prevention of diarrhoeaupon oral administration of an IBAT inhibitor.

The invention also relates to the use of the formulation disclosedherein in the manufacture of a medicament for the treatment orprevention of diarrhoea upon oral administration of an IBAT inhibitor.The invention further relates to a method for the treatment orprevention of diarrhoea upon oral administration of an IBAT inhibitor,comprising administering to a mammal in need of such treatment orprevention therapeutically effective amounts of an IBAT inhibitor and ofthe formulation disclosed herein.

In a preferred embodiment, the invention relates to the formulationdisclosed herein, for use in the treatment or prevention of bile aciddiarrhoea upon treatment of a liver disease, such as a cholestatic liverdisease, comprising oral administration of an IBAT inhibitor. Inparticular, the invention relates to the formulation disclosed hereinfor use in the treatment or prevention of diarrhoea upon treatment ofAlagilles syndrome (ALGS), progressive familial intrahepatic cholestasis(PFIC), primary biliary cirrhosis (PBC), primary sclerosing cholangitis(PSC), autoimmune hepatitis, cholestatic pruritus, non-alcoholic fattyliver disease (NAFLD) or non-alcoholic steatohepatitis (NASH) comprisingoral administration of an IBAT inhibitor.

In another embodiment, the invention relates to a method for thetreatment or prevention of bile acid diarrhoea upon treatment of a liverdisease comprising oral administration of an IBAT inhibitor, comprisingadministering to a mammal in need of such treatment or prevention atherapeutically effective amount of the formulation disclosed herein. Inparticular, the invention relates to such a method for the treatment orprevention of diarrhoea wherein the liver disease is Alagilles syndrome(ALGS), progressive familial intrahepatic cholestasis (PFIC), primarybiliary cirrhosis (PBC), primary sclerosing cholangitis (PSC),autoimmune hepatitis, cholestatic pruritus, non-alcoholic fatty liverdisease (NAFLD) or non-alcoholic steatohepatitis (NASH).

A liver disease as defined herein is any bile acid-dependent disease inthe liver and in organs connected therewith, such as the pancreas,portal vein, the liver parenchyma, the intrahepatic biliary tree, theextrahepatic biliary tree, and the gall bladder. Liver diseases include,but are not limited to an inherited metabolic disorder of the liver;inborn errors of bile acid synthesis; congenital bile duct anomalies;biliary atresia; neonatal hepatitis; neonatal cholestasis; hereditaryforms of cholestasis; cerebrotendinous xanthomatosis; a secondary defectof BA synthesis; Zellweger's syndrome; cystic fibrosis (manifestationsin the liver); alpha1-antitrypsin deficiency; Alagilles syndrome (ALGS);Byler syndrome; a primary defect of bile acid (BA) synthesis;progressive familial intrahepatic cholestasis (PFIC) including PFIC-1,PFIC-2, PFIC-3 and non-specified PFIC; benign recurrent intrahepaticcholestasis (BRIC) including BRIC1, BRIC2 and non-specified BRIC;autoimmune hepatitis; primary biliary cirrhosis (PBC); liver fibrosis;non-alcoholic fatty liver disease (NAFLD); non-alcoholic steatohepatitis(NASH); portal hypertension; general cholestasis; jaundice duringpregnancy; jaundice due to drugs; intrahepatic cholestasis; extrahepaticcholestasis; primary sclerosing cholangitis (PSC); gall stones andcholedocholithiasis; malignancy causing obstruction of the biliary tree;pruritus due to cholestasis or jaundice; pancreatitis; chronicautoimmune liver disease leading to progressive cholestasis; hepaticsteatosis; alcoholic hepatitis; acute fatty liver; fatty liver ofpregnancy; drug-induced hepatitis; iron overload disorders; hepaticfibrosis; hepatic cirrhosis; amyloidosis; viral hepatitis; and problemsin relation to cholestasis due to tumours and neoplasms of the liver, ofthe biliary tract and of the pancreas.

Disorders of fatty acid metabolism and glucose utilization disordersinclude, but are not limited to, hypercholesterolemia, dyslipidemia,metabolic syndrome, obesity, disorders of fatty acid metabolism, glucoseutilization disorders, disorders in which insulin resistance isinvolved, and type 1 and type 2 diabetes mellitus.

IBAT inhibitors are often referred to by different names. As usedherein, the term “IBAT inhibitors” should be understood as alsoencompassing compounds known in the literature as ApicalSodium-dependent Bile Acid Transporter Inhibitors (ASBTI's), bile acidtransporter (BAT) inhibitors, ileal sodium/bile acid cotransportersystem inhibitors, apical sodium-bile acid cotransporter inhibitors,ileal sodium-dependent bile acid transport inhibitors, bile acidreabsorption inhibitors (BARI's) and sodium bile acid transporter (SBAT)inhibitors.

IBAT inhibitors that can be used in combination with the bile acidsequestrant formulation disclosed herein include, but are not limitedto, benzothiazepines, benzothiepines,1,4-benzothiazepines,1,5-benzothiazepines and 1,2,5-benzothiadiazepines.

Suitable examples of IBAT inhibitors that can be used in combinationwith the bile acid sequestrant formulation disclosed herein include, butare not limited to, the compounds disclosed in WO 93/16055, WO 94/18183,WO 94/18184, WO 96/05188, WO 96/08484, WO 96/16051, WO 97/33882, WO98/03818, WO 98/07449, WO 98/40375, WO 99/35135, WO 99/64409, WO99/64410, WO 00/47568, WO00/61568, WO 00/38725, WO 00/38726, WO00/38727, WO 00/38728, WO 00/38729, WO 01/68096, WO 02/32428, WO03/061663, WO 2004/006899, WO 2007/009655, WO 2007/009656, DE 19825804,EP 864582, EP 489423, EP 549967, EP 573848, EP 624593, EP 624594, EP624595, EP 624596, EP 0864582, EP 1173205 and EP 1535913.

Particularly suitable IBAT inhibitors are those disclosed in WO01/66533, WO 02/50051, WO 03/022286, WO 03/020710, WO 03/022825, WO03/022830, WO 03/091232, WO 03/106482 and WO 2004/076430, and especiallythe compounds selected from the group consisting of:

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N-(carboxymethyl)carbamoyl]-benzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N′—((S)-1-carboxyethyl)carbamoyl]-benzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,5-benzothiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxypropyl)-carbamoyl]benzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((R)-1-carboxy-2-methylthioethyl)-carbamoyl]benzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxypropyl)carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((R)-1-carboxy-2-methylthioethyl)carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxy-2-methylpropyl)-carbamoyl]benzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxy-2-(R)-hydroxypropyl)carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxybutyl)carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxyethyl)carbamoyl]-benzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N′—((S)-1-carboxypropyl)carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,5-benzothiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxyethyl)carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxy-2-methylpropyl)-carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine;and

1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-1′-phenyl-1′-[N′-(carboxymethyl)carbamoyl]methyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,5-benzothiazepine;

or a pharmaceutically acceptable salt thereof.

Other particularly suitable IBAT inhibitors are those disclosed inWO99/32478, WO00/01687, WO01/63637, WO03/022804, WO 2003/058628 and WO2008/058630, and especially the compounds selected from the groupconsisting of:

1-[4-[4-[(4R,5R)-3,3-dibutyl-7-(dimethylamino)-2,3,4,5-tetrahydro-4-hydroxy-1,1-dioxido-1-benzothiepin-5-yl]phenoxy]butyl]4-aza-1-azoniabicyclo[2.2.2]octanemethanesulfonate;

1-[[4-[[4-[3,3-dibutyl-7-(dimethylamino)-2,3,4,5-tetrahydro-4-hydroxy-1,1-dioxido-1-benzothiepin-5-yl]phenoxy]methyl]phenyl]methyl]-4-aza-1-azoniazabicyclo[2.2.2]octanechloride;

1-[[5-[[3-[(3S,4R,5R)-3-butyl-7-(dimethylamino)-3-ethyl-2,3,4,5-tetrahydro-4-hydroxy-1,1-dioxido-1-benzothiepin-5-yl]phenyl]amino]-5-oxopentyl]amino]-1-deoxy-D-glucitol;and

potassium((2R,3R,4S,5R,6R)-4-benzyloxy-6-{3-[3-((3S,4R,5R)-3-butyl-7-dimethylamino-3-ethyl-4-hydroxy-1,1-dioxo-2,3,4,5-tetrahydro-1H-benzo[b]thiepin-5-yl)-phenyl]-ureido}-3,5-dihydroxy-tetrahydro-pyran-2-ylmethyl)sulphate,ethanolate, hydrate.

An effective amount of the cholestyramine formulation according to theinvention can be any amount containing more than or equal to about 100mg of cholestyramine, such as more than or equal to about 250 mg, 500mg, 750 mg, 1000 mg, 1250 mg, 1500 mg, 1750 mg or 2000 mg ofcholestyramine. For example, the effective amount of cholestyramine canbe between 100 mg and 5000 mg such as between 250 mg and 2500 mg,between 250 mg and 2000 mg, between 500 mg and 2500 mg, between 500 mgand 2000 mg, or between 750 mg and 2000 mg.

A unit dose of the cholestyramine formulation according to the inventionmay comprise from 200 to 300 mg of cholestyramine, such as from 220 to280 mg of cholestyramine, such as from 240 to 260 mg of cholestyramine.A unit dose preferably comprises about 250 mg of cholestyramine. Thedaily dose can be administered as a single dose or divided into one,two, three or more unit doses.

The frequency of administration of the formulation as disclosed hereincan be any frequency that reduces the bile acid malabsorption conditionwithout causing any significant adverse effects or toxicity to thepatient. The frequency of administration can vary from once or twice aweek to several times a day, such as once a day or twice a day. Thefrequency of administration can furthermore remain constant or bevariable during the duration of the treatment.

Several factors can influence the frequency of administration and theeffective amount of the formulation that should be used for a particularapplication, such as the severity of the condition being treated, theduration of the treatment, as well as the age, weight, sex, diet andgeneral medical condition of the patient being treated.

The invention is further illustrated by means of the following examples,which do not limit the invention in any respect. All cited documents andreferences are incorporated herein by reference.

Abbreviations

HPLC High Performance Liquid Chromatography

PTFE Polytetrafluoroethylene

RH Relative humidity

rpm revolutions per minute

UHPLC Ultra High Performance Liquid Chromatography

UV-Vis Ultraviolet-visible spectroscopy

EXAMPLES Example 1

Extrusion Experiments

All experiments were performed on a 100-200 g scale. The dry ingredients(cholestyramine, the vinylpyrrolidone-based polymer and/ormicrocrystalline cellulose) were mixed in the amounts indicated below.Water was added in portions of 50-100 gram with 3 minutes of mixingbetween each addition. When an acrylate copolymer was included in theexperiment, it was added as a 2% w/w dispersion in water (20 g acrylatecopolymer (aqueous dispersion 30%) added up to 300 g water). A finalportion of pure water was added, if necessary. In each experiment, thetotal amount of liquid added was between 1.7 and 2.3 times the amount ofsolid material (w/w).

The wet mass was transferred to an extruder equipped with a 1.5 mmscreen, operated at 25 rpm (revolutions per minute) and the extrudatewas collected on a stainless steel tray. Approximately 100 g of theextrudate was run in the spheronizer for 1 minute at a speed of 730 rpm.The spheronized material was then transferred to stainless steel trays,placed in a drying oven and dried for 16 hours at 50° C. The yield wascalculated as the fraction of pellets that pass through a 1.6 mm sievebut are retained on a 1.0 mm sieve.

Friability testing was performed using the equipment and proceduredescribed in European Pharmacopoeia 8.0, test 2.9.7. The pellets weresieved on a 500 μm sieve to remove any loose dust before weighing.

The results using copovidone and Eudragit® RL 30 D are shown in Table 1,and the results using povidone and other Eudragit® copolymers are shownin Table 2.

TABLE 1 Amount (% w/w) Chole- Eudragit ® Yield Friability Entrystyramine Copovidone MCC RL 30 D (%) (%) 1 100 0 0 0 * * 2 90 0 10 0 * *3 70 0 30 0 39 1.6 4 70 6 24 0 * * 5 70 0 26 4 * * 6 70 6 20 4 85 0.1 780 3 15 2 * * 8 85 7.5 4.5 3 92 0.6 9 90 6 4 0 * * 10 90 0 6 4 * * 11 900 0 10 * * 12 90 6 0 4 85 1.4 13 90 10 0 0 87 1.2 14 91 9 0 0 82 0.5 1592 8 0 0 83 1.5 16 93 7 0 0 78 1.0 17 94 6 0 0 * * 18 91 6 0 3 84 0.3 1992 6 0 2 82 1.6 20 93 6 0 1 * * 21 85 6 8 1 81 3.5 22 80 6 13 1 85 0.823 92 5 0 3 70 2.0 24 93 5 0 2 * * 25 85 5 8 2 54 7.1 26 80 5 13 2 739.1 * = extrusion followed by spheronization did not lead to pellets.

TABLE 2 Amount (% w/w) Chole- Yield Friability Entry styramine PovidoneMCC Eudragit ® (%) (%) 1 85 7.5 4.5 3% w/w 79 0.2 FS 30 D 2 85 7.5 4.53% w/w 24 0.8 L 30 D-55 3 85 7.5 4.5 3% w/w 88 0.5 NE 30 D 4 85 7.5 4.53% w/w 96 0.9 NM 30 D 5 85 7.5 4.5 3% w/w 82 0.8 RS 30 D

Example 2

Preparation of Pellets

Pellets with a composition according to Table 1, entry 8, weremanufactured at a batch size of 200 g in the extrusion step and 100 g inthe spheronization step. 170 g cholestyramine, 15 g copovidone and 9 gmicrocrystalline cellulose were charged into a planetary mixer. Themixer was operated at intermediate speed and the liquid was slowly addedin portions with mixing between each addition. First 300 g water with 20g Eudragit® RL 30 D (30% dry weight) was added in three equal portions,with mixing for 3 minutes between each addition. Finally 40 g pure waterwas added and mixing was performed for additionally 30 seconds. The wetmass was then transferred to the extruder. The extruder was equippedwith a 1.5 mm screen, operated at 25 rpm and the extrudate was collectedon a stainless steel tray. Approximately 100 g of the extrudate was runin the spheronizer for 1 minute at a speed of 730 rpm. The spheronizedmaterial was then transferred to stainless steel trays, placed in adrying oven and dried for 16 hours at 50° C. The dried pellets weresieved and the fraction between 1 mm and 1.4 mm was collected.

Example 3

Formulations A-C for pH- and Diffusion-Controlled Release

The cholestyramine pellets of Example 2 were formulated with a colonrelease coating comprising an diffusion controlled inner coating basedon polyethyl acrylate-co-methyl methacrylate-co-trimethylammonioethylmethacrylate chloride) and an enteric outer coating based onhydroxypropyl methylcellulose acetate succinate.

Three formulations were prepared with different amounts of poly(ethylacrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylatechloride) in the inner coating, as follows:

Formulation A: 100% Eudragit® RL 30 D

Formulation B: 50% Eudragit® RL 30 D+50% Eudragit® RS 30 D

Formulation C: 100% Eudragit® RS 30 D

The pellets composition for a unit dose comprising 250 mg cholestyramineis shown below.

Amount Ingredient (mg/dose) Cholestyramine 250 Copovidone (Kollidon ®VA64 Fine) 22.1 Microcrystalline cellulose (Avicel ® PH102) 13.2Poly(ethyl acrylate-co-methyl 8.8 methacrylate-co-trimethylammonioethylmethacrylate chloride) 1:2:0.2 (Eudragit ® RL 30 D) Total 294.1

Inner Coating

A glycerol monostearate (GMS) emulsion containing GMS, polysorbate 80and triethyl citrate was prepared according to general instructions fromEvonik. The emulsion was mixed with Eudragit RL30D/RS30D dispersion (30%w/w). The composition of the inner coating film, based on dry weight, isshown below. The concentration, based on dry weight of the applieddispersion, is 19.8% (w/w).

Ingredient Amount Inner coating (w/w) Poly(ethyl acrylate-co-methyl 90.4methacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.2(Eudragit ® RL 30 D) or 1:2:0.1 (Eudragit ® RS 30 D) Triethyl citrate4.5 Glycerol monostearate 45-55 (Kolliwax ® GMS II) 3.6 Polysorbate 80(Tween ® 80) 1.5

The coating layer was applied using a Hüttlin Kugelcoater HKC005; batchsize 75 g. The coating process was performed with an air inlettemperature of 45° C., resulting in a product temperature of 27-29° C.Air flow was adjusted to achieve an appropriate fluidization of thepellets during the coating. The coating was applied to the pellets so asto obtain a weight gain of 10%. After the coating, the pellets wereheat-treated at 40° C. for 24 hours.

Outer Coating

The enteric coating was prepared by mixing 7% w/w hypromellose acetatesuccinate, 2.45% w/w triethyl citrate, 2.1% w/w talc, 0.21% w/w sodiumlauryl sulphate and 88.24% w/w water for 30 min with an overhead stirrerat low temperature, <15° C. The composition of the outer coating film,based on dry weight, is shown below. The coating liquid was kept below15° C. during the coating process.

Ingredient Amount Outer coating (w/w) Hypromellose acetate succinate(AQOAT AS HF) 59.5 Triethyl citrate 20.8 Talc, micronized 17.9 Sodiumlauryl sulphate (Kolliphor ® SLS Fine) 1.8

The coating layer was applied using a Hüttlin Kugelcoater HKC005; batchsize 75 g. The coating process was performed with an air inlettemperature of 55° C., resulting in a product temperature of 32° C. Airflow was adjusted to achieve an appropriate fluidization of the pelletsduring the coating. The enteric coating was applied to the pellets so asto obtain a weight gain of 40% (based on the weight of the coatedpellets after application of the inner coating). After the coating, thepellets were heat-treated at 40° C./75% RH for 48 hours.

The coated pellets may be encapsulated in capsules, e.g. hard gelatinecapsules. Details for the final formulations (on dry weight basis) areshown below:

Dose weight: 452.9 mg Cholestyramine: 250 mg (55%) Inner coating: 29.4mg Outer coating: 129.4 mg Total coating: 158.8 mg (35%)

Example 4

Formulation D for pH- and Diffusion-Controlled Release

The cholestyramine pellets of Example 2 were formulated with a colonrelease coating comprising a diffusion controlled inner coating based onpoly(ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethylmethacrylate chloride), an enteric coating based on hydroxypropylmethylcellulose acetate succinate and finally coated with fumed silicato prevent sticking of the pellets during storage.

The pellets composition for a unit dose comprising 250 mg cholestyramineis shown below.

Amount Ingredient (mg/dose) Cholestyramine 250 Copovidone (Kollidon ®VA64 Fine) 22.1 Microcrystalline cellulose (Avicel ® PH102) 13.2Poly(ethyl acrylate-co-methyl 8.8 methacrylate-co-trimethylammonioethylmethacrylate chloride) 1:2:0.2 (Eudragit ® RL 30 D) Total 294.1

Inner Coating

A glycerol monostearate (GMS) emulsion containing GMS, polysorbate 80and triethyl citrate was prepared according to general instructions fromEvonik. The emulsion was mixed with Eudragit RS30D dispersion (30% w/w).The composition of the inner coating film, based on dry weight, is shownbelow. The concentration, based on dry weight of the applied dispersion,is 20.0% (w/w).

Ingredient Amount Inner coating (w/w) Poly(ethyl acrylate-co-methyl78.75 methacrylate-co-trimethylammonioethyl methacrylate chloride)1:2:0.1 (Eudragit ® RS 30 D) Triethyl citrate 15.75 Glycerolmonostearate 45-55 (Kolliwax ® GMS II) 3.95 Polysorbate 80 (Tween ® 80)1.55

The coating solution was applied using a Vector FL-M-1 apparatus. Theinitial batch size was 500 g. The coating process was performed with anair inlet temperature of 41-43° C., resulting in a product temperatureof 23-30° C. The air flow was adjusted to achieve an appropriatefluidization of the pellets during the coating. The coating was appliedto the cholestyramine pellets so as to obtain a weight gain of 10%. Thecoated pellets were then heat-treated at 40° C. for 50 hours and 30minutes.

Enteric Coating

The enteric coating was prepared by mixing 7% w/w hypromellose acetatesuccinate, 2.45% w/w triethyl citrate, 2.1% w/w talc, 0.21% w/w sodiumlauryl sulphate and 88.24% w/w water for 30 minutes with an overheadstirrer at low temperature, <15° C. The composition of the outer coatingfilm, based on dry weight, is shown below. The coating liquid was keptbelow 15° C. during the coating process.

Ingredient Amount Outer coating (w/w) Hypromellose acetate succinate(AQOAT AS HF) 59.5 Triethyl citrate 20.8 Talc, micronized 17.9 Sodiumlauryl sulphate (Kolliphor ® SLS Fine) 1.8

The coating layer was applied using a Vector FL-M-1 apparatus. Thecoating process was performed with an air inlet temperature of 35-55°C., resulting in a product temperature of 28-32° C. Air flow wasadjusted to achieve an appropriate fluidization of the pellets duringthe coating. The enteric coating was applied to the pellets so as toobtain a weight gain of 40% (based on the weight of the coated pelletsafter application of the inner coating).

Final Coating

Directly after the enteric coating, fumed silica was applied onto thecoated pellets by spraying a 5% suspension of Aerosil® 200 in water ontothe pellets. The coating was applied using the same equipment with aninlet temperature of 40-41° C., resulting in a product temperature of30° C. The air flow was adjusted to achieve an appropriate fluidizationof the pellets during the coating. The coating was applied to thecholestyramine pellets so as to obtain a weight gain of 1% (w/w). Thecoated pellets were finally in-process heat-treated at 60° C. for 30minutes in the coating equipment.

The coated pellets may be encapsulated in capsules, e.g. hard gelatinecapsules. Details for the final formulations (on dry weight basis) areshown below:

Dose weight: 457.4 mg Cholestyramine: 250 mg (55%) Inner coating: 29.4mg Enteric coating: 129.4 mg Anti-sticking coating 4.5 mg Total coating:163.3 mg (36%)

Example 5

Sequestration Assay

The sequestering capacities of formulations A, B and C were determinedin a simplified assay, simulating the pH of the stomach and the smallintestine. The sequestration was determined by measuring the decreasingamount of cholic acid in an aqueous solution. The USP DissolutionApparatus 2 (paddle) Ph. Eur. 2.9.3 was used.

Sequestration at pH 5.5

An amount of formulation A, B or C corresponding to 250 mgcholestyramine was added to a vessel containing 500 mL of a bufferedsolution of cholic acid (0.192 mg/mL), pH 5.5 and the contents werestirred at 75 rpm for 6 hours. Samples of the solution were withdrawn atdifferent time points and analysed for cholic acid by HPLC using aThermo Hypersil Gold column, 50 mm×2.1 mm, particle size 1.9 μm; columntemperature 60° C.; mobile phase 30:70 acetonitrile:phosphate buffer (pH3.0); flow rate 0.75 mL/min. 5 replicate samples were analysed for eachformulation and the average values were calculated.

Sequestration at pH 6.8 or 7.4

An amount of formulation A, B or C corresponding to 250 mgcholestyramine was added to a vessel containing 250 mL 0.1 Mhydrochloric acid solution (pH 1) and the contents were stirred at 75rpm for 2 hours. 250 mL of a solution of cholic acid in potassiumhydroxide/potassium phosphate buffer solution was then added to thevessel, giving a buffered solution of cholic acid (0.192 mg/mL) with pH6.8 or 7.4. After 1 minute of mixing, a first sample was removed. The pHwas thereafter verified and if necessary adjusted to 6.8 or 7.4 byaddition of the appropriate amount of 0.1 M potassium hydroxidesolution. The solution was thereafter mixed for an additional 6 hours.Samples of the solution were withdrawn at different time points andanalysed for cholic acid by HPLC using a Thermo Hypersil Gold column, 50mm×2.1 mm, particle size 1.9 μm; column temperature 60° C.; mobile phase30:70 acetonitrile:phosphate buffer (pH 3.0); flow rate 0.75 mL/min. 5replicate samples were analysed for each formulation and the averagevalues were calculated.

The sequestration profiles for formulations A-C are shown in FIG. 1. ThepH of 5.5 is slightly lower than the pH normally observed in theduodenum, although it may occur in some patients and healthy persons. Atthis pH, sequestration is limited for all formulations (FIG. 1A).Sequestration at pH 6.8 is representative for the conditions in theileum. At this pH, formulation A, B and C gave 52%, 42% and 34%sequestration, respectively, after 4 hours (FIG. 1B). At pH 7.4,formulation A, B and C gave 54%, 42% and 36% sequestration,respectively, after 4 hours (FIG. 1C). This pH is probably slightlyhigher than the pH normally observed in the distal ileum.

The coated pellets of formulations A, B and C showed no or only minordisintegration. Visual inspection of the pellets revealed that thecoating was intact after stirring for 6 hours. In contrast, the uncoatedpellets of Example 2, when stirred in a phosphate buffer (50 mM, pH 6.8)at 300 rpm (propeller stirrer), fully disintegrated within 1 minute and25 seconds.

Example 6

In Vitro Determination of the Sequestering Capacity of Formulation A-CUnder Simulated Conditions for the Gastrointestinal Tract

The sequestering capacities of formulations A, B and C were studied inthe Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) asdeveloped by ProDigest (Ghent, Belgium). The simulator was adapted toevaluate the sequestering capacity of binding bile salts underphysiological conditions representative for fasted stomach, smallintestine and proximal colon. The liquid media representative of thefasted stomach and small intestine have previously been described byMarzorati et al. (LWT-Food Sci. Technol. 2015, vol, 60, p. 544-551). Theliquid medium for the proximal colon comprises a SHIME® matrixcontaining a stable microbial community representative for the humancolon. A method for obtaining a stable microbial community of the humanintestine is described by Possemiers et al. (FEMS Microbiol. Ecol. 2004,vol. 49, p. 495-507) and references therein. The sequestration wasdetermined by measuring the decreasing amount of bile acids in anaqueous solution. A 40:40:20 (w/w) mixture of cholic acid (CA),chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA) was used as arepresentative mixture of human bile salts (Carulli et al., Aliment.Pharmacol. Ther., 2000 vol. 14, issue supplement s2, p. 14-18).

A comparative experiment was conducted to which pure cholestyraminepowder was added. A control experiment to which no cholestyramine wasadded was conducted in order to monitor the degradation of the bilesalts under the colonic conditions used in the assay.

Each experiment was performed in triplicate to account for biologicalvariation.

Fasted Stomach

Amounts of formulations A, B and C corresponding to 91 mg ofcholestyramine and the pure cholestyramine (91 mg) were dosed to 14 mLfasted stomach liquid medium (pH 1.8). The digests were incubated for 1hour at 37° C.

Small Intestine

After one hour of stomach incubation, 5.6 mL pancreatic juice (pH 6.8)containing the defined 40:40:20 mixture of bile salts (46.7 mM) wasadded. The small intestine digests were incubated for 2 hours at 37° C.and samples were taken after 0, 60 and 120 minutes.

Proximal Colon

After two hours of small intestine incubation, 42 mL of a full SHIMEmatrix (pH 6.0) originated from the ascending colon of a SHIME systemwas added. The colon digests were incubated for 24 hours at 37° C. andsamples were collected every hour for the first 6 hours and then at 19 hand at 24 h.

Sample Analysis

The concentration of free bile salts in the samples was assessed bymeans of HPLC. A calibration curve was used to calculate theconcentrations of CA, CDCA and DCA in the samples. One mL of each samplewas centrifuged for 2 min at 5000 g. 500 μL of the supernatant was mixedwith 500 μL of an 80:20 (v:v) mixture of methanol and phosphate buffer,vigorously vortexed, filtered through a 0.2 μm PTFE filter and injectedin a Hitachi Chromaster HPLC equipped with a UV-Vis detector. The threebile salts were separated by a reversed-phase C18 column (Hydro-RP, 4μm, 80 Å, 250×4.6 mm, Synergi). The separation was performed underisocratic conditions at room temperature, using a 80:20 (v:v) mixture ofmethanol and phosphate buffer as the mobile phase. The analysis wasperformed at 0.7 mL/min during 23 minutes and the bile salts weredetected at 210 nm. The injection volume was set at 20 μL for stomachand small intestine samples and 50 μL for colon samples.

The full SHIME® matrix that was used for the colonic incubationscontains (degraded) bile salts originating from BD Difco™ Oxgall, adehydrated fresh bile extract from bovine origin (Catalog Number212820). Although the exact composition of this mixture is unknown, ahigher quantity of free bile salts might be expected in the colonsamples. The values of the background (i.e. blank sample where no mix ofbile salts was added) were therefore subtracted from each sample inorder to take into account the ‘baseline’ of free bile salts present inthe total SHIME® matrix.

The table below shows the relative concentrations of CA, CDCA and DCA,respectively, after 2 hours of small intestinal incubations (“SI-2”) andafter 4 hours of colonic incubations (“C-4”), as well as theproportional reduction in the period therebetween.

CA CDCA DCA Formulation SI-2 C-4 Δ SI-2 C-4 Δ SI-2 C-4 Δ Control 1 21 192 50 48 5 51 46 Cholestyramine 59 95 36 90 93 3 89 99 11 A 16 66 49 2265 43 25 75 50 B 22 72 50 30 73 43 31 79 49 C 18 71 53 17 68 52 19 75 57

The relative concentrations of CA, CDCA and DCA (%) vs. incubation timeare shown in FIGS. 2, 3 and 4, respectively. The graphs include thesamples taken after 0 hours and 2 hours of small intestinal (SI)incubation, and after 0, 2, 4, 6, 19 and 24 hours of colonic (C)incubation.

The figures confirm the effect and extent of microbial salt metabolismin the gut (e.g. deconjugation, dehydrogenation and dehydroxylation) asobserved by the significant decrease in bile salt levels in the controlsamples to which no cholestyramine was added.

It can be seen that the three formulations offered a protection of theactive compound during the small intestinal incubation. Whereas pure(uncoated) cholestyramine led to a reduction of 59% of CA, 90% of CDCAand 89% of DCA already after 2 hours of small intestinal incubation (seethe comparative experiment), formulations A, B and C gave rise to muchlower reduction of bile salts during this period. During the smallintestinal incubation, formulation C showed the best results, with only18%, 17% and 19% reduction of CA, CDCA and DCA, respectively. During thefirst four hours of the colonic incubation, all three formulations gaverise to a large reduction of bile salts. Formulation C showed the bestresults, with 71% sequestration of CA, 68% sequestration of CDCA and 75%sequestration of DCA, corresponding to a 53%, 52% and 57% reduction ofCA, CDCA and DCA, respectively.

Example 7

Stability Test

Hard capsules comprising formulation C (250 mg cholestyramine) werestored at 25° C./60% RH during 11 months.

After 0, 3, 6 and 11 months of storage, the capsules were analysed forcholestyramine and water content. Also, the sequestering capacity of theformulation was determined using the assay described in Example 5. Theresults are shown in the table below.

Time (months) Analysis Units 0 3 6 11 Cholestyramine content mg/capsule250 246 245 % of initial 100 98.4 98.0 Water content % 18.3 17.8 16.9Sequestration pH 5.5 (6 h) % 7 10 5 5 Sequestration pH 1 (2 h) + % 34 3536 36 pH 6.8 (4 h)

The invention claimed is:
 1. An oral formulation for targeted deliveryof cholestyramine to the colon, comprising: a plurality of extruded andspheronized pellets, each extruded and spheronized pellet comprising a)a homogenous mixture of at least 70% w/w cholestyramine and i. acombination of at least 6% w/w of a vinylpyrrolidone-based polymer andat least 2% w/w of an acrylate copolymer; or ii. a combination of atleast 5% w/w of a vinylpyrrolidone-based polymer and at least 3% w/w ofan acrylate copolymer; or iii. a combination of at least 6% w/w of avinylpyrrolidone-based polymer, at least 1% w/w of an acrylate copolymerand at least 10% w/w microcrystalline cellulose; wherein the pelletsexhibits a friability of less than 2.1% as measured using the EuropeanPharmacopoeia 8.0, test 2.9.7; and b) a diffusion-controlled innercoating surrounding each extruded and spheronized pellet; and c) anenteric outer coating.
 2. The formulation according to claim 1, whereinthe diffusion-controlled inner coating is elastic.
 3. The formulationaccording to claim 1, wherein the diffusion-controlled inner coatingcomprises poly(ethyl acrylate-co-methylmethacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.2,poly(ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethylmethacrylate chloride) 1:2:0.1, or a combination thereof.
 4. Theformulation according to claim 1, wherein the enteric outer coatingcomprises hydroxypropyl methylcellulose acetate succinate.
 5. Theformulation according to claim 1, wherein the diameter of the uncoatedextruded and spheronized pellet is from 1000 to 1400 μm.
 6. Theformulation according to claim 1, wherein the uncoated extruded andspheronized pellet also comprises microcrystalline cellulose.
 7. Theformulation according to claim 1, wherein the uncoated extruded andspheronized pellet is free of microcrystalline cellulose.
 8. Theformulation according to claim 1, wherein each of the uncoated extrudedand spheronized pellets comprises at least 80% w/w cholestyramine. 9.The formulation according to claim 8, wherein each of the uncoatedextruded and spheronized pellets comprises at least 85% w/wcholestyramine.
 10. The formulation according to claim 1, wherein thecholestyramine content of the final formulation (on dry weight basis) isat least 50% w/w.
 11. The formulation according to claim 10, wherein thecholestyramine content of the final formulation (on dry weight basis) isat least 55% w/w.
 12. The formulation according to claim 1, wherein thetotal amount of coating in the final formulation (on dry weight basis)is less than 40% w/w.
 13. The formulation according to claim 12, whereinthe total amount of coating in the final formulation (on dry weightbasis) is less than 35% w/w.
 14. The formulation according to claim 1,wherein the formulation is capable of releasing more than 70% w/w of thecholestyramine in the formulation in the colon.
 15. The formulationaccording to claim 1, wherein the formulation is capable of releasingless than 30% w/w of the cholestyramine in the formulation in the smallintestine.
 16. The formulation according to claim 1, wherein theformulation is contained within a capsule.
 17. The formulation accordingto claim 1, wherein the formulation is contained within a sachet.
 18. Amethod for treating or preventing bile acid malabsorption in a patientin need thereof, the method comprising administering to the patient atherapeutically effective amount of an oral formulation comprising: a) aplurality of extruded and spheronized pellets, each extruded andspheronized pellet comprising a homogenous mixture of at least 70% w/wcholestyramine and i. a combination of at least 6% w/w of avinylpyrrolidone-based polymer and at least 2% w/w of an acrylatecopolymer; or ii. a combination of at least 5% w/w of avinylpyrrolidone-based polymer and at least 3% w/w of an acrylatecopolymer; or iii. a combination of at least 6% w/w of avinylpyrrolidone-based polymer, at least 1% w/w of an acrylate copolymerand at least 10% w/w microcrystalline cellulose; wherein the pelletsexhibits a friability of less than 2.1% as measured using the EuropeanPharmacopoeia 8.0, test 2.9.7; and b) a diffusion-controlled innercoating surrounding said extruded and spheronized pellets; and c) anenteric outer coating.
 19. The method according to claim 18, wherein thebile acid malabsorption is the result of ileal disease (Crohn'sdisease), ileal resection or ileal bypass, the result of overproductionof bile acids or defective feedback inhibition of hepatic bile acidsynthesis, or the result of cholecystectomy, vagotomy, small intestinalbacterial overgrowth (SIBO), coeliac disease, pancreatic insufficiency(chronic pancreatitis, cystic fibrosis), pancreatic transplant,radiation enteritis, collagenous colitis, microscopic colitis,lymphocytic colitis, ulcerative colitis or irritable bowel syndrome(IBS-D).
 20. A method of treating or preventing bile acid diarrhoea in apatient in need thereof, the method comprising administering to thepatient a therapeutically effective amount of an oral formulationcomprising: a) a plurality of extruded and spheronized pellets, eachextruded and spheronized pellet comprising a homogenous mixture of atleast 70% w/w cholestyramine and i. a combination of at least 6% w/w ofa vinylpyrrolidone-based polymer and at least 2% w/w of an acrylatecopolymer; or ii. a combination of at least 5% w/w of avinylpyrrolidone-based polymer and at least 3% w/w of an acrylatecopolymer; or iii. a combination of at least 6% w/w of avinylpyrrolidone-based polymer, at least 1% w/w of an acrylate copolymerand at least 10% w/w microcrystalline cellulose; wherein the pelletsexhibits a friability of less than 2.1% as measured using the EuropeanPharmacopoeia 8.0, test 2.9.7; and b) a diffusion-controlled innercoating surrounding and in contact with said extruded and spheronizedpellets; and c) an enteric outer coating.
 21. The method according toclaim 20, wherein the patient is also administered an IBAT inhibitor viaoral administration.
 22. The method according to claim 21, wherein thepatient has a cholestatic liver disease.
 23. The method according toclaim 21, wherein the IBAT inhibitor is1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-α-[N—((S)-1-carboxypropyl)-carbamoyl]-4-hydroxybenzyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine,or 1,1-dioxo-3,3-dibutyl-5-phenyl-7-methylthio-8-(N—{(R)-1′-phenyl-1′-[N′-(carboxymethyl)carbamoyl]methyl}carbamoylmethoxy)-2,3,4,5-tetrahydro-1,5-benzothiazepine;or a pharmaceutically acceptable salt thereof.
 24. A process for thepreparation of coated extruded and spheronized pellets comprising aplurality of extruded and spheronized pellets, each extruded andspheronized pellet comprising a) a homogenous mixture of at least 70%w/w cholestyramine and i. a combination of at least 6% w/w of avinylpyrrolidone-based polymer and at least 2% w/w of an acrylatecopolymer; or ii. a combination of at least 5% w/w of avinylpyrrolidone-based polymer and at least 3% w/w of an acrylatecopolymer; or iii. a combination of at least 6% w/w of avinylpyrrolidone-based polymer, at least 1% w/w of an acrylate copolymerand at least 10% w/w microcrystalline cellulose; wherein the pelletsexhibits a friability of less than 2.1% as measured using the EuropeanPharmacopoeia 8.0, test 2.9.7; and b) a diffusion-controlled innercoating surrounding said extruded and spheronized pellets; and c) anenteric outer coating; the process comprising the steps of: a) preparingthe extruded and spheronized pellets in a method comprising: i) mixingthe dry ingredients; ii) adding water, and the acrylate copolymer, toobtain a wet mass; iii) extruding the wet mass; iv) spheronizing theextrudate; and v) drying the obtained extruded and spheronized pellets;b) applying the diffusion-controlled inner coating to the extruded andspheronized pellets; and c) applying the enteric outer coating to theextruded and spheronized pellets coated with the diffusion-coated innercoating.
 25. An oral formulation for targeted delivery of cholestyramineto the colon, comprising: a plurality of extruded and spheronizedpellets, each extruded and spheronized pellet comprising a) at least 70%w/w cholestyramine and i. a combination of at least 6% w/w of avinylpyrrolidone-based polymer and at least 2% w/w of an acrylatecopolymer; or ii. a combination of at least 5% w/w of avinylpyrrolidone-based polymer and at least 3% w/w of an acrylatecopolymer; or iii. a combination of at least 6% w/w of avinylpyrrolidone-based polymer, at least 1% w/w of an acrylate copolymerand at least 10% w/w microcrystalline cellulose; wherein thecholestyramine, the vinylpyrrolidone-based polymer, the acrylatecopolymer, a liquid, and, if present, the microcrystalline cellulose arecombined to form a wet mass that is extruded and spheronized to form theplurality of extruded and spheronized pellets, wherein the pelletsexhibits a friability of less than 2.1% as measured using the EuropeanPharmacopoeia 8.0, test 2.9.7; and b) a diffusion-controlled innercoating surrounding each extruded and spheronized pellet; and c) anenteric outer coating.